I wantedcreate afor a long timebikewithgear boxin thebottom bracket
as IExpandeda rimrearhuband built acustomcoaster,
Icould not havegear....andI missed it!
I'minspired by oldbikes(1900),andtractor mowergearbox!
I puttwo weeksto get the ideaand createplans
andabout 2 months torealizethe gearbox!
there are threespeeds andaxisdriveand outputare the same
theselection systemis brass
plexiglassboxisto see themechanism
FirstI madeplans andgear ratio
Planswere madetothescaleto facilitatemanufacturing andvarioustestsof setting up
the systemconsists ofa shaft on whicha gear isdrivenall the timeand the twootherturn in theblank
whenyou changethespeedwhich wasledstartsto rotatein the airand it isanother thattakes over
for machininggearssupports, aspecial machine(mortiser) was used
I had todisassemblea lot ofspeedfreewheelbikein order to makethis arrangement
Ithenjust solderthe sprockets ontheir support
then, and stillbrass, Imachined"sliding"
it slideson the shaftand causes afinger, whichthanks toa spring,causesthe pinionthatis desired, while leavingthe others free
just asa system oftractormower!
- Bottom4sprocketsrotateat the same time
-Righttherethe output gear(the piecewith theredlinesallows to seetherotation)
-Top left, the threesprocketsrotateindependentlyof each other(thebrassShiftingused to lockthe one youwant)
here you can see in works
manufactureof the boxto receive themechanism
I askedafriendsto machine thebearinglocation
for the restI did everythingby hand,witha hole sawand ajig saw....not easy!
canperceivethe selectorandbearing housings
space that Ishows withmy fingersused to placethe gearboxon the bike
to assemblethe pieces ofplexiglass,I used aspecialglueplanned forthis
tediousbutimportant step, polishing!
I used severalgradesandpaper:
100, 240, 400,800, 1000, 2500 and 4000
thenpolishhasis sufficientvehicle body
Thisisthe same methodtorenovatetheplastic headlights;-)
someonetold meit looks likeasprocketsaquarium......lol
I was missing6 mmin order to closethe boxproperly ....
SoI usedorangeplexiglassto fill this gap
because I loveorange
becauseaccording to the angleof view, reflectionsgives the impressionthat the entiregearboxis coloredsothatthere isveryfeworange
a smallplexiglasscovercanmake a little moresealedall
here is general aspect
here is the new system
I dono moredetailsthan thatthe bikebecause for methe main subject isthe gearbox!
a bikecustomissimple to dofor someone whoused to doit
evenwhenI putsome pictures of thebikeas I havealso spenttime on it
on the picturesit isa friendwho drives thebike
on thevideois me